--- 1/draft-ietf-bfd-secure-sequence-numbers-07.txt 2021-03-22 13:39:10.900358711 -0700 +++ 2/draft-ietf-bfd-secure-sequence-numbers-08.txt 2021-03-22 13:39:10.920359209 -0700 @@ -1,25 +1,25 @@ Network Working Group M. Jethanandani Internet-Draft Kloud Services Updates: 5880 (if approved) S. Agarwal Intended status: Standards Track Cisco Systems, Inc -Expires: June 19, 2021 A. Mishra +Expires: September 9, 2021 A. Mishra O3b Networks A. Saxena Ciena Corporation A. Dekok Network RADIUS SARL - December 16, 2020 + March 8, 2021 Secure BFD Sequence Numbers - draft-ietf-bfd-secure-sequence-numbers-07 + draft-ietf-bfd-secure-sequence-numbers-08 Abstract This document describes a security enhancement for the sequence number used in BFD control packets. This document updates RFC 5880. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. @@ -27,25 +27,25 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on June 19, 2021. + This Internet-Draft will expire on September 9, 2021. Copyright Notice - Copyright (c) 2020 IETF Trust and the persons identified as the + Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -128,28 +128,27 @@ the symmetric algorithm to produce the ciphertext, which is then inserted in place of the sequence number. Upon receiving the BFD Control packet, the receiver decrypts the ciphertext using the same provisioned shared key to produce the received sequence number. It compares the received sequence number against the expected sequence number. The mechanism used for comparing is an implementation detail (implementations may pre- calculate the expected sequence number, or decrypt the received sequence number before comparing against expected value). To - tolerate dropped frames, the receiver MUST compare the received - sequence number against the current expected sequence number - (previous received sequence number + 1) and N subsequent expected - sequence numbers (where N is greater than or equal to the detect - multiplier). Note: The first sequence number can be obtained using - the same logic as used in determining Local Discriminator value for - the session or by using a random number. - + tolerate dropped frames, the receiver must compare the received + sequence number against the current expected sequence number. BFD + [RFC5880] mentions that received sequence number should be between + (bfd.RcvAuthSeq(+1) to bfd.RcvAuthSeq+(3*Detect Mult) inclusive. + Note: The first sequence number can be obtained using the same + principles stated in BFD [RFC5880] i.e. (using bfd.AuthSeqKnown and + bfd.RcvAuthSeq) K: symmetric key S: sequence number S': encrypted sequence number OR ciphertext result O: original RFC 5880 packet with monotonically increasing sequence number f(S, K) = S', where f is a symmetric encryption algorithm @@ -172,23 +171,23 @@ authentication. On successful authentication, it decrypts the ciphertext with the same key used to encrypt it, in order to obtain the original sequence number. If it is greater than the previously received monotonically increasing sequence number, then the receiver knows it's a valid sequence number. 4. Impact of using a hash Under this proposal, every packet's sequence number is encoded in ciphertext. Therefore, there is some impact on the system and its - performance while encryption/decryption. As security measures go, - this enhancement greatly increases the security of the packet with or - without authentication of the entire packet. + performance while doing encryption/decryption. As security measures + go, this enhancement greatly increases the security of the packet + with or without authentication of the entire packet. 5. IANA Considerations This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC. 6. Security Considerations @@ -210,21 +209,21 @@ BFD session to be operationally down. The symmetric algorithm and key size will determine the difficulty for an attacker to decipher the key from the transmitted BFD frames. The sequential nature of the payload (sequence numbers) simplifies the decoding of the key. It is, therefore, recommended to use longer keys or more secure symmetric algorithms. 7. Acknowledgements - The authors would like to thank Jeff Hass and Reshad Rahman for their + The authors would like to thank Jeff Haas and Reshad Rahman for their reviews of and suggestions for the document. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, .